def get_breadcrumb(category_model):    """返回面包屑导航数据"""    # 定义一个变量用来包装面包屑导航数据    breadcrumb = {}    breadcrumb['cat3'] = category_model    breadcrumb['cat2'] = category_model.parent    cat1 = category_model.parent.parent  # 查询到一级    goods_channel_model_qs = cat1.goodschannel_set.all()  # 查询到一级所对应的商品频道查询集    goods_channel_model = goods_channel_model_qs[0]  # 获取商品频道查询集中0角标的频道模型对象    cat1.url = goods_channel_model.url  # 给一级类别模型对象多添加一个url    breadcrumb['cat1'] = cat1    return breadcrumb